Osteochondral allograft transplantation of the knee: a review of indications,techniques, outcome and how to promote biology

Articular cartilage lesions of the knee in young and active patients can result in significant disability. Osteochondral allografts (OCAs) can be used to treat challenging articular lesions of the knee ≥2 cm², either as a primary or revision procedure. They have the advantage of restoring the articular surface with mature hyaline cartilage without any size limitations or donor site morbidity. Chondrocyte viability above 70% at the time of implantation is thought to be desirable, and consequently OCA implantation within the 28-day graft expiration date can result in logistical challenges. No randomized trials exist; however, excellent clinical outcomes have been reported, along with good long-term survivorship up to 20 years. Several factors can influence the outcome after OCA use, including patient selection, anatomical location, associated pathologies and several biological considerations. The purpose of this article is to review the latest evidence on treatment indications, graft storage and surgical techniques, biological considerations, patient outcomes and rehabilitation after surgery.     

Changes in local and network brain activity after stereotactic thermocoagulation in patients with drug-resistant epilepsy

Objective

Stereoelectroencephalography-guided radiofrequency thermocoagulation (SEEG-guided RF-TC) aims to reduce seizure frequency by modifying epileptogenic networks through local thermocoagulative lesions. Although RF-TC is hypothesized to functionally modify brain networks, reports of changes in functional connectivity (FC) following the procedure are missing. We evaluated, by means of SEEG recordings, whether variation in brain activity after RF-TC is related to clinical outcome.

Methods

Interictal SEEG recordings from 33 patients with drug-resistant epilepsy (DRE) were analyzed. Therapeutic response was defined as a >50% reduction in seizure frequency for at least 1 month following RF-TC. Local (power spectral density [PSD]) and FC changes were evaluated in 3-min segments recorded shortly before (baseline), shortly after, and 15 min after RF-TC. The PSD and FC strength values after thermocoagulation were compared with baseline as well as between the responder and nonresponder groups.

Results

In responders, we found a significant reduction in PSD after RF-TC in channels that were thermocoagulated for all frequency bands (p = .007 for broad, delta and theta, p <.001 for alpha and beta bands). However, we did not observe such PSD decrease in nonresponders. At the network level, nonresponders displayed a significant FC increase in all frequency bands except theta (broad, delta, beta band: p <.001; alpha band: p <.01), although responders showed a significant FC decrease in delta (p <.001) and alpha bands (p <.05). Nonresponders showed stronger FC changes with respect to responders exclusively in TC channels (broad, alpha, theta, beta: p >.05; delta: p = .001).

Significance

Thermocoagulation induces both local and network-related (FC) changes in electrical brain activity of patients with DRE lasting for at least 15 min. This study demonstrates that the observed short-term modifications in brain network and local activity significantly differ between responders and nonresponders and opens new perspectives for studying the longer-lasting FC changes after RF-TC.     

Favorable outcome of hematopoietic stem cell transplantation in late-onset Krabbe disease

BackgroundLate-onset Krabbe disease is a disorder with autosomal recessive inheritance caused by a deficiency in galactocerebrosidase (GALC) activity. Its late-onset form usually shows slow disease progression with atypical symptoms including spastic paresis. The efficacy of hematopoietic stem cell transplantation (HSCT) in late-onset Krabbe disease has not been fully established.Case ReportWe describe the case of a patient with late-onset Krabbe disease showing progressive spastic paraparesis. At the age of 18, one and a half years after the development of symptoms, the patient underwent HSCT. After HSCT, the patient's GALC activity returned to a normal level and the lesions in the brain and spinal cord became faint on images. Over two and a half years after the HSCT, the patient's gait remained spastic, however, an improvement in gait speed and modified Rankin Scale score was observed. No severe adverse events occurred during this period.ConclusionOur experience reported herein provides additional evidence for a favorable course in HSCT conducted in the early course of late-onset Krabbe disease.